Polymethine dye lasers

ABSTRACT

Merocyanine dyes which contain a pyran nucleus as part of the intercyclic chain are useful as laser dyes. These dyes are used in solution with a non-interfering solvent to form lasing media useful in dye lasers. Such lasers generally include a reservoir for containing the laser dye solution and a pumping energy source operably associated therewith for producing stimulated emission of the laser dye solution.

United States Patent [191 McColgin et al.

[ Mar. 19, 1974 POLYMETHINE DYE LASERS [75] Inventors: William C.McColgin; Frank G.

Webster, both of Rochester, NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Nov. 11, 1971 [21] Appl. No.: 197,892

[52] US. Cl. 331/945 L, 252/3012 R, 260/240 R [51] Int. Cl. H015 3/20[58] Field of Search 260/240 R; 252/3012 R;

[56] References Cited UNITED STATES PATENTS 3,194,805 7/1965 Brooker eta1. 260/240 R 3,521,187 7/1970 Snavely et a1 252/3011 R 3,541,47011/1970 Lankard et al 252/3012 R 2,965,486 12/1960 Brooker et a1 96/127Primary Examiner-Daniel E. Wyman Assistant Examiner-A. P. DemetsAttorney, Agent, or Firm-Robert W. Hampton [57] ABSTRACT 15 Claims, N0Drawings POLYMETHINE DYE LASERS This invention relates to lasers andmore particularly to organic dye lasers and to the use of certainrigidized nitrogen-containing dyes capable of lasing when properlyexcited.

Lasers (acronym for light amplification by stimulated emission ofradiation) or optical masers (acronym for microwave amplification bystimulated emission of radiation) are light amplifying devices whichproduce high intensity coherent monochromatic light concentrated in awell collimated beam commonly called a laser beam. There are severaluses for such laser beams. Since the beam can be sharply focused, it canproduce energy densities suitable for drilling, welding, cutting, etc.One potential application of laser beams is in the field ofcommunications where the optical spectrum represents almost limitlessbandwidth and information carrying capacity.

It is desirable to have lasers which are operable at many differentwavelengths in the light spectrum including infrared, visible andultraviolet regions. Since the wavelength emitted by a specific energytransition in a laser medium is tunable over only a small portion of thespectrum, it is necessary to provide a number of materials adapted foruse as active laser media at various light frequencies. Many of thematerials discovered thus far which are capable of acting as laser mediahave been in the solid and gaseous states. It is also known that certainorganic dyes in solution can operate as liquid or organic dye lasers. Ofthe range of materials useful as lasing media, organic lasing dyesprovide certain advantages. A wide range of organic dye lasers isavailable to provide stimulated emission (lasing) over a broad range ofthe spectrum. Secondly, organic dye lasers are generally capable ofbeing tuned to emit over a range of wavelengths, this being incontradistinction to the essentially single wavelength capability oflasing emission characterizing gas and solid lasers. Thirdly, organicdye lasers provide an economical lasing medium when compared to gas andsolid lasers, and they do not suffer from disadvantages such as crackingand optical imperfections that are particularly associated with solidlasers.

The ability to selectively tune organic dye lasers derives from thebroad band fluorescence characteristic of the component dye. Such laserscan be tuned to emit at wavelengths along substantially the entirefluorescence band of the dye by interposing a dispersive element such asa diffraction grating or a prism.

The operation of a laser is achieved as a result of the phenomenon thatexcited atoms or molecules can emit a photon or quantum of light, whichphoton or quantum can itself trigger another excited atom or molecule toemit its photon prematurely. This process is designated stimulatedemission.

The excitation of organic lasing dyes can be achieved by subjecting thedye, under controlled conditions such as will be described herein, to asuitable source of energy such as bombarding it with electrons orilluminating it with a high energy source. conventionally, illuminationis utilized for liquid laser materials. Excitation of a liquid lasermedium by illumination is generally termed optical pumping or merelypumping. Pumping sources include, for example, sources such as giantpulse lasers, xenon and argon arc flash tubes as well as are dischargetubes containing only air or other gaseous mixtures.

Various arrangements of laser apparatus can be used. A laser structureparticularly adapted for organic dye liquid laser media is described bySorokin et al., IBM Journal, V. ll, p. 148 (1967). Advantageous laserapparatus structures usually include an optically resonant cavitycontaining a reservoir of a liquid laser medium or a liquid laser bodydisposed within a thin-walled quartz cylinder. Typically, the reservoiris part of a closed system through which the dye solution is circulatedduring lasing operation. Thus, localized heating which can causerefractive discontinuities and potential breakdown of the dye iseffectively prevented. To provide an energy source for exciting theatoms of the laser material, the laser body can be surroundedconcentrically by a lamp, such as one containing as annular regionwithin an outer thick-walled quartz cylinder. The annular region cancontain an air-argon mixture and have electrodes which are operablyconnected to a low inductance capacitor charged by a standard highvoltage supply. Desirably, coaxially disposed at either end of theoptically resonant cavity are opposed internally reflective cavity endssuch as mirrors.

When optical pumping is used, the light source emits light havingwavelengths within at least one absorption band of the lasing medium.The absorbed light causes molecular electrons in the medium to shift inenergy level. Molecular electrons exist either in a singlet state (twoelectrons spinning in opposite directions) or a triplet state (twoelectrons spinning in the same direction). The ground state is theunexcited state for molecular electrons and has the lowest energy.Typically, the ground state in almost all molecules is a singlet(designated S one of many possible energy levels in the singlet state.When the pumping source is activated, the resultant light pulse entersthe laser body and photons of energy of appropriate absorptivewavelength are absorbed by active molecules in the body and cause theelectrons of such molecules to shift from an initial low energy level (Sto a high energy level from which emissive transition occurs.

In operation, the molecular electrons of the laser medium are desirablypumped" to higher excited states of the singlet system by intense energyinputs. It is thought that they then first undergo transitions from suchexcited states to the lowest excited state (designated S). Afterdiminishing in energy level to the lowest excited singlet, the moleculecan relinquish its remaining excess energy radiatively or nonradiativelyfrom S to S, non-radiatively from S to a triplet state and thenradiatively or non-radiatively from the lowest excited triplet state toS. Generally, laser emission consists of optical emission resulting fromtransitions from S to various vibrational modes of S. Susceptibility totriplet formation upon pumping is deleterious due to typicalnon-radiative energy losses resulting from triplet to S transitions.Also, if there is significant overlap between the triplet absorption andeither the pump bands or lasing emission bands, laser action generallywill be impeded or will fail en'tirely. Additionally, advantageous laseremission can occur only when the population of molecules established atthis higher energy level in the laser body by such light pumping exceedsthe population of molecules remaining at the initial low energy level, acondition conventionally designated population inversion or inversion ofenergy states."

Upon reaching an inversion of energy states, individual molecules of thehigh energy level population undergo emissive transition spontaneously,shifting to a terminal low energy level as described herein with aconcomitant emission of light. A portion of the spontaneously emittedlight is usually reflected back and forth through a resonant opticalcavity structure, such as previously described, between its internallyreflective ends. As this light passes through the laser body in multiplebidirectional reflections, it induces other molecules of the enlargedhigh energy level population to undergo premature light emissivetransitions as noted herein. This produces more light, which augmentsthe bidirectionally reflected light in the cavity to induce stillfurther light emissive transitions. A rising pulse of bidirectionallyreflected light quickly develops in the cavity, reaching aquantitatively large value as the induced emissive transition ofmolecules from the high energy level population increases. If one of thereflective cavity ends is partially transmissive, as is typically thecase, a portion of the intense reflected light pulse passes through theone end and out of the cavity to constitute the laser output light pulseor the laser beam.

Although many advances have been made in the field of organic dyelasers, we have now found a new class of lasing dyes. It is, therefore,an object of this invention to provide a novel class of lasing dyeswhich, upon lasing, emit at a variety of wavelengths.

Another object of this invention is to provide novel liquid lasingmedia.

These and other objects and advantages are obtained through the use,with dye lasers having a reservoir means containing a laser dye solutionand a pumping energy source capable of producing stimulated emission ofthe solution which comprises a lasing concentration of dye in anon-interfering solvent (i.e., one that does not inhibit stimulatedemission), that dye being a polymethine laser dye of the merocyaninetype which contains a pyran nucleus as part of the intercyclic chain.

The dyes useful in this invention can be represented by the structuralformula:

wherein:

R represents an alkyl radical having one to about ten and preferablyabout one to about four carbon atoms and including substituted alkylradicals having such substituents as sulfo, carboxy, dialkylamino(having one to about four carbon atoms in the alkyl moieties), hydroxy,alkoxy (having one to about four carbon atoms in the alkyl moiety),acyloxy, alkoxycarbonyl (having one to about four carbon atoms in thealkyl moiety) and an aryl radical; an alkenyl radical having two toabout ten and preferably two to about four carbon atoms and includingsubstituted alkenyl radicals; and a monoeylic aryl radical includingsubstituted monocylic aryl radicals, e.g., phenyl, halophenyl,

(chloro, bromo, etc), alkylphenyl (having one to about four carbon atomsin the alkyl moiety) alkoxyphenyl (having one to about four carbon atomsin the alkyl moiety), hydroxyphenyl, etc;

R represents a hydrogen atom, an alkyl radical having one to about sixand preferably about one to about two carbon atoms and a monoacylic arylradical as described for R above;

n represents an integer having a value of O or 1;

m represents an integer having a value of O, 1 or 2;

Either carbon atom in the dimethine group having the subscript m canalso be substituted with an alkyl radical, an aralkyl radical or an arylradical, e.g., phenyl, naphthyl, etc;

D and D each represent a member selected from the group consisting of acyano radical, an alkoxycarbonyl radical having from one to about fourcarbon atoms in the alkyl moiety, an acyl radical having one to aboutfour carbon atoms in the alkyl portion and including aracyl radicals(e.g., phenylcarbonyl, etc). a substituted sulfonyl radical having suchsubstituents as alkyl radicals having one to five carbon atoms, arylradicals and aryloxy and when the moieties D and D are taken togetherwith the carbon atom to which they are attached, represent a radicalhaving the structure: lll.

wherein Q represents the non-metallic atoms necessary to complete afiveor six-membered ring of the type used in merocyanine dyes andtypically contains at least one hetero atom selected from nitrogen,oxygen, sulfur or selenium. Exemplary cyclic nuclei of the type used inmerocyanine dyes and as represented by Formula lll above, include anisoxazolinone nucleus (e.g., 3-phenyl-2-isoxazolin-5-one,3-methyl-2-isoxazolin- 5-one, etc.), an oxindole nucleus (e.g.,l-alkyl-2,3- dihydro-2-oxindoles, etc), a 2,4,6-triketohexahydropyrimidine nucleus (e.g., barbituric acid or2-thiobarbituric acid, as well as their l-alkyl (e.g., l-methyl,l-ethyl, l-n-propyl, l-n-heptyl, etc), or l,3-dialkyl (e.g.,l,3-dimethyl, l,3-diethyl, l,3-di-npropyl, l,3-diisopropyl,l,3-dicyclohexyl, l,3-di(2- methoxyethyl), l,3-di(dialkylaminoalkyl),l-alkyl-3- (2-morpholinoalkyl), etc), or l,3-diaryl (e.g., 1,3-diphenyl, l,3-di(4-chlorophenyl), l,3-di-(4-ethoxycarbonylphenyl),l,3-di(dialkylaminophenyl), etc), or 1- aryl (e.g., l-phenyl,l-p-chlorophenyl, lp-ethoxycarbonylphenyl, etc), or l-alkyl-3-aryl(e.g., l-ethyl-3-phenyl, l-(n-heptyl-3-phenyl), etc) derivatives, a2(3H)-imidazo[l,2-a]pyridone nucleus; 05,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]pyrimidine nucleus (e.g.,5,7-dioxo-3-phenyl-6,7-dihydr0-5- thiazolo[ 3,2-a1pyrimidine nucleus), a2-thio-2,4-oxazolidinedione nucleus (i.e., a

2-thio- 2,4-(3H,5H)-oxazoledione nucleus) (e.g., 3-ethyl-2-thio-2,4-oxazolidinedione, etc), a thianaphthenone nucleus(e.g., 3(2H)-thianaphthenone, 3(2H)- thianaphthenone-l,l-dioxide, etc),a 2-thio-2,5- thiazolidinedione nucleus (i.e., a 2-thio-2,5-(3H,4H)-thiazoledione nucleus) (e.g., 3-ethyl-2-thio-2,5- (3H,4H)-thia-zolidinedione, etc), a 2,4- thiazolidinedione nucleus (e.g.,2,4-thiazolidinedione,

atoms at least one of which is nitrogen and the other is selected fromnitrogen, oxygen or sulfur;

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus containing from five to six atoms in the heterocyclic ring, suchas those selected from the group consisting of a thiazole nucleus (e.g.,thiazole, 4-methyl-thiazole, 4-phenylthiazole, 5- methylthiazole,S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole,4-(2-thienyl)- thiazole, etc), a

benzothiazole nucleus (e.g., benzothiazole, 4- chlorobenzothiazole,5-chlorobenzothiazole, 6- chlorobenzothia-zole, 7-chlorobenzothiazole,4- methylbenzothiazole, S-methyl-benzothiazole, 6- methylbenzothiazole,5-bromobenzothiazole, 6- bromobenzothiazole, 4-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, 5- methoxybenzothiazole,6-methoxybenzo-thiazole, 5- iodobenzothiazole, -iodobenzothiazole, 4-

ethoxybenzo-thiazole, S-ethoxybenzothiazole, tetrahydrobenzothiazole,5,6-dimethoxybenzothiazole, 5,6- dimethylenebenzothiazole,5-hydroxy-benzothiazole, -hydroxybenzothiazole, etc), a naphthothiazolenucleus (e.g., naphtho[ l ,2]thiazole, naphtho[2,l thiazole, naphtho[2,3Ithiazole, 5- methoxynaphtho[2,l ]thiazole, S-ethoxynaphtho[2,llthiazole, 8- methoxynaphtho[ 1,2]thiazole, 7-methoxy-5-hydroxy-benzoselenazole, tetrahydrobenzoselenazole, etc), anaphtho-selenazole nucleus (e.g., naphtho[ 1,2]selenazole, naphtho- [2,l]selenazole, etc), a thiazoline nucleus (e.g., thiazoline,4-methylthiazoline, etc), a 2-quinoline nucleus (e.g., quinoline,3-methylquinoline, S-methylquinoline,

7-methylquinoline, 8-methylquinoline, 6- chloroquinoline,8-chloroquinoline, 6- methoxyquinoline, 6-ethoxyquinoline,6-hydroxyquinoline, S-hydroxyquinoline, etc), a 4-quinoline nucleus(e.g., quinoline, 6-methoxyquinoline, 7- methylquinoline,S-methylquino-line, etc), a lisoquinoline nucleus (e.g., isoquinoline,3,4- dihydroisoquinoline, etc), a benzimidazole nucleus (e.g.,l,3-diethylbenzimidazole, l-ethyl-3- phenylbenzimidazole, etc), a3,3-dialkylindolenine nucleus (e.g., 3,3-dimethylindolenine, 3,3,5-trimethylindolenine, 3,3,7-trimethylindolenine, etc), a Z-pyridinenucleus (e.g., pyridine, S-methylpyridine,

etc), a 4-pyridine nucleus (e.g., pyridine etc), animidazo[4,5-b]-quinoxaline nucleus (e.g.,l,3-dialkylimidazo[4,5-b]quinoxaline such asl,3-diethylimidazo[4,5-blquinoxaline, 6-chlorol,3-diethylimidazo[4,5-b]quinoxaline, etc, 1,3

dialkenylimidazo-[4,5-b]quinoxaline such asl,3-diallylimidazo[4,5-b]quinoxaline, 6-chloro-l,3-diallylimidazo[4,5-b]quinoxaline, etc,l,3-diarylimidazo[4,5-b]quinoxaline such as 6,7-dichloro-l,3-

diphenyl-imidazo[4,5-b]quinoxaline, 1,3-diphenylimidazo[4,5-b]quinoxaline, 6-chloro-l ,3-diphenylimidazo[4,5-b]quinoxaline, l,3-bis(pchlorophenyl)imidazo[4,5-b]quinoxaline) etc.

As used herein, the term lasing concentration refers to a concentrationsufficient to promote, under appropriate conditions such as thosementioned herein, stimulated emission of the laser dye solution.Generally, concentrations of from about 10 to 10 molar are employed,with solutions of from 10 to 10 molar concentrations being preferred formaximum output energies. Still wider variations in concentration can beused for particular operations, if desired.

Representative useful non-interfering solvents which do not inhibitstimulated emission are water; alkanols, including mono-, diandpolyhydric alcohols containing from one to about six carbon atoms andpreferably from two to about four carbon atoms, e.g., methanol, ethanol,isopropanol, isopropanediol, butanol, etc; and aryl alcohols such asvarious benzene derivatives wherein the hydroxy radical is attacheddirectly to the aryl nucleus or is attached thereto through an alkylenemoiety having from one to about four carbon atoms, e.g., phenol,methylphenol, resorcinol, phenylcarbinol, methylphenylcarbinol, etc.Other solvents include fluorinated organic alcohols corresponding to thealcohols described above and discussed further in copending Drexhageapplication Ser. No. 149,055, filed June 1, 1971, and entitled LASERMEDIA CONTAINING FLUORINATED ALCOHOLS, now US. Pat. No. 3,736,524,issued May 29, 1973. Also useful are heterocyclic compounds having anitrogen heteroatom (e.g., pyridine, 2,6-dimethylpyridine, etc), andlower alkyl ketones such as dimethylketone. Of course, combinations ofliquids can be used as can other solvents known to be useful in the dyelaser art.

The present lasing media can be used in a variety of laser apparatus. Alaser structure particularly adapted for testing organic dye liquidlaser media is that degiant pulse from a 530.0 nm. frequency doubled,neodymium glass laser. The dye lasing medium is placed in a cuvettewhich is located between two dielectric mirrors which form a nearlyhemispherical dye laser cavity. The light from the excitation or pumpingsource passes through one of the dielectric mirrors into thedye-containing cuvette and along the optical axis of the cavity. A beamsplitter is used to sample the output from the excitation source inorder to determine the wavelength of lasing.

EXAMPLE 1 The dye 4-dicyanomethylene-2-[(3-ethyl-2-benzoxazolinylidine)propenyl]-6-methyl-4H-pyran is mixed in methanol toan optical density of about 2.0 in a cm. dye cuvette. The cuvette isplaced between two dielectric mirrors as described above. The dye isfound to lase at a wavelength of about 604 nm.

EXAMPLE 2 The dye of Example 1 is tested in an apparatus consisting of aSorokin type coaxial flashlamp around a lasing cavity for opticalexcitation of the solution as described in U.S. Pat. No. 3,521,187,issued July 21, 1970, with the energy for the lamp stored by a CornellDubilier lpffast discharge capacitor. A M solution of the dye inmethanol is placed in the cavity and is observed to lase.

EXAMPLE 3 Example I is repeated except that the dye is 4-dicyanomethylene-2-[(3-ethyl-2-benzothiazolinylidene)propenyl]-6-phenyl-4H-pyran and the solvent isacetone. The dye lases at about 682 EXAMPLE 4 Example I is repeatedexcept that the dye is 1,3- diethyl-S-{2-[(3-ethyl-2-benzothiazolinylidene)methyl]-6-phenyl-4H-pyran-4-ylidene} barbituric acid and the solvent is acetone.The dye lases at about 602 nm.

EXAMPLE 5 Example I is repeated except that the dye is 4-dicyanomethylene-2-methyl-6-[( l,3 ,3-trimethyl-2-indolinylidene)propenyl]-4H-pyran and the solvent is acetone. The dyelases atabout 614 nm.

EXAMPLE 6 Example 1 is repeated except that the dye is 1,3- diethyl-S-{2-methyl-6-[(1,3,3-trimethyl-2-indolinylidene)propenyl]-4H-pyran-4-ylidene} barbituric acid. The dyelases at about 666 nm.

EXAMPLE 7 Example 1 is repeated except that the dye is 1,3-

8 diethyl-5- i2[(3-ethyl-2-benzoxazolylidene )propenyl]-6-methyl4l-l-pyran-4-ylidene} barbituric acid. The dye lases at about 648nm.

EXAMPLE 8 Example 1 is repeated except that the dye is 1,3- diethyl-S-2- l-ethylnaphtho[ 1,2]thiazolin-2-ylidene)methyl]-6-methyl-4H-pyran-4-ylidene} barbituric acid. The dyelases at about 576 nm.

EXAMPLE 9 Example 1 is repeated except that the dye is 1,3- diethyl-S-2-[(3-ethyl-2-benzothiazolinylidene)methyl1-6-methyl-4H-pyran-4-ylidene} -2-thiobarbituric acid. The dye lases withtwo peaks at about 569 and 610 nm.

EXAMPLE 10 Example 1 is repeated except that the dye is 1,3- diethyl-S-2-[(3-ethyl-2-benzothiazolinylidene)methyl1-6-methyl-4H-pyran-4-ylidene} barbituric acid. The dye lases at about 560nm.

EXMAPLE l 1 Example 1 is repeated except that the dye is 4-dicyanomethylene-2-[(1-ethylnaphtho[1,2]thiazolin-2-ylidene)propenyl]-6-methyl-4H-pyran. The dye lases at about 656 nm.

EXAMPLE 12 Example 1 is repeated except that the dye is 4-dicyanomethylene-2-[ 3-ethyl-2- lerizothiazolinylidene) propenyl I -6-methyl-4H-pryan and the solvent is acetone. The dye lases at about 630EXAMPLE 13 Example 1 is repeated except that the dye is 4-dicyanomethylene-2-[ 3-ethyl-2-benzothiazolinylidene)methyl]-6-phenyl4H-pyran and the solvent isacetone. The dye lases at about 584 nm.

EXAMPLE 14 g 1 Example 1 is repeated except that the dye is l,3dieth- L5 ethyl 2 -benz othiazolinylidene)propenyl1-6-methyl-4H-pyran-4-ylidene} barbituric acid and the solvent is acetone.The dye lases at about 668 nm.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

We claim:

1. A dye laser comprising means containing a laser dye solution and apumping energy source operably coupled therewith for producing apopulation inversion in said solution and means optically coupled withsaid solution for stimulating emission therefrom during said populationinversion, said dye solution comprising a lasing concentration, in anoninterfering solvent, of a dye having the formula as follows:

wherein:

R represents a member selected from the group consisting of an alkylradical having one to about 10 carbon atoms, an alkenyl radical havingtwo to about 10 carbon atoms and a phenyl radical;

R represents a member selected from the group consisting of a hydrogenatom, an alkyl radical having one to about six carbon atoms and a phenylradical;

n represents an integer having a value of O or 1; m represents aninteger having a value of O, l or 2;

D and D each represent a member selected from the group consisting of acyano radical, an alkoxycarbonyl radical having one to about four carbonatoms in the alkyl moiety, an acyl radical having one to about fourcarbon atoms in the alkyl portion thereof, a phenylcarbonyl radical, analkyl sulfonyl radical having one to five carbon atoms in the alkylmoiety, an aryl substituted sulfonyl radical, an aryloxy substitutedsulfonyl radical and when D and D are taken together with the carbonatom to which they are attached, represent a radical of the structure:

in which Q represents the non-metallic atoms necessary to complete acyclic nucleus selected from the group consisting of an isoxazolinonenucleus, an oxindole nucleus, a 2,4,6-triketo-hexahydropyrirnidinenucleus, a 2(3H)-imidazo[1,2-a]pyridone nucleus, a 5,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]pyrimidine nucleus, a2-thio-2,4-oxazolidinedione nucleus, a thianaphthenone nucleus, a2-thio-2,5-thiazolidinedione nucleus, a 2,4-thiazolidinedione nucleus, athiazolidinone nucleus, a 4-thiazolinone nucleus, a 2-imino-2-oxazolin-4-one nucleus, a 2,4-imidazolidinedione nucleus, a 1,3- indanedionenucleus, a dione nucleus, a tetrone nucleus, or a 2-imidazolin-5-onenucleus; and

Z represents the nonmetallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, athianaphtheno-7',6',4,5-thiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, 21 naphthoxazole nucleus. :1 selenazole nucleus, abenzoselenazole nucleus, a naphthoselenazole nucleus, a thiazolinenucleus, a Z-quinoline nucleus, 21 4-quinoline nucleus, a l-isoquinolinenucleus, a benzimidazole nucleus, a 3,3-dialkylindolenine nucleus, a 2-pyridine nucleus, a 4-pyridine nucleus and an imidazo[4,5-b]quinoxalinenucleus. 2. The invention as described in claim 1 wherein said dye ispresent in a concentration of about 10 to about 65 coupled therewith forproducing a population inversion in said solution and means opticallycoupled with said solution for stimulating emission therefrom duringsaid population inversion, said dye solution comprising a 5 lasingconcentration, in a non-interfering solvent, of a dye having the formulaas follows:

m represents an integer having a value of 0, l or 2;

D and D each represent a cyano radical and when D and D are takentogether with the carbon atom to which they are attached, represent theatoms necessary to complete a 2,4,6- triketohexahydropyrimidine nucleus;and

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, 21thianaphtheno-7',6,4,5-thiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, a naphthoxazole nucleus, a selenazole nucleus, abenzoselenazole nucleus, a naphthoselenazole nucleus, a thiazolinenucleus, a 2-quinoline nucleus, a l-isoquinoline nucleus, abenzimidazole nucleus, a 3,3- dialkylindolenine nucleus, a 2-pyridinenucleus, and an imidazo[4,5-b]-quinoxaline nucleus.

4. A dye laser comprising means containing a laser dye solution and apumping energy source operably coupled therewith for producing apopulation inversion in said solution and means optically coupled withsaid solution for stimulating emission therefrom during said populationinversion, said dye solution comprising a lasing concentration, in anon-interfering solvent, of a dye having the formula as follows:

wherein:

R represents a member selected from the group consisting of an alkylradical having one to about 10 carbon atoms, an alkenyl radical havingtwo to about 10 carbon atoms and a phenyl radical;

R represents a member selected from the group consisting of a hydrogenatom, an alkyl radical having one to about six carbon atoms and a phenylradical;

m represents an integer having a value of O, l or 2;

D and D each represent a cyano radical and when D and D' are takentogether with the carbon atom to which they are attached, represent theatoms necessary to complete a 2,4,6- triketohexahydropyrimidine nucleus;and

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, a naphthoxazole nucleus and a Z-pyridine nucleus.

5. The invention as described in claim 4 wherein R is an alkyl radicalhaving one or two carbon atoms.

6. A method of producing coherent laser emission in the operation of adye laser in the wavelength range of from about 500 to 1,000 nmcomprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom, said solution containing between about to about 10molar concentration ofa lasing dye in a non-interfering solvent, saiddye having the formula as follows:

wherein:

R represents a member selected from the group consisting of an alkylradical having one to about 10 carbon atoms. an alkenyl radical havingtwo to about 10 carbon atoms and a phenyl radical;

R represents a member selected from the group consisting of a hydrogenatom, an alkyl radical having one to about six carbon atoms and a phenylradical;

n represents an integer having a value of 0 or 1; m represents aninteger having a value of O, l or 2;

D and D each represent a member selected from the group consisting of acyano radical, an alkoxycarbonyl radical having one to about four carbonatoms in the alkyl moiety, an acyl radical having one to about fourcarbon atoms in the alkyl portion thereof, a phenyl carbonyl radical, analkyl sulfonyl radical having one to five carbon atoms in the alkylmoiety, an aryl substituted sulfonyl radical, an aryloxy substitutedsulfonyl radical, and when D and D are taken together with the carbonatom to which they are attached, represent a radical of the structure:

in which Q represents the non-metallic atoms necessary to complete a acyclic nucleus selected from the group consisting of an isoxazolinonenucleus, an oxindole nucleus, a 2,4,6-triketo-hexahydropyrimidinenucleus, a 2(3l-l)-imidazo[ l,2-a]pyridone nucleus, a 5,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]pyrimidine nucleus, a2-thio-2,4-oxazolidinedione nucleus, a thianaphthenone nucleus, a2-thio-2,S-thiazolidinedione nucleus, a 2,4-thiazolidinedione nucleus, athiazolidinone nucleus, a 4-thiazolinone nucleus, a 2-imino-2-oxazolin-4-one nucleus, a 2,4-imidazolidinedione nucleus, a l ,3- indanedionenucleus, a dione nucleus, a tetrone nucleus, or a 2-imidazolin-5-onenucleus; and

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, athianaphtheno-7,6,4,5-thiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, 21 naphthoxazole nucleus, 21 selenazole nucleus, abenzoselenazole nucleus, a naphthoselenazole nucleus, a thiazolinenucleus, a 2-quinoline nucleus, a 4-quinoline nucleus, a l-isoquinolinenucleus, a benzimidazole nucleus, a 3,3-dialkylindolenine nucleus, a 2-pyridine nucleus, 21 4-pyridine nucleus and an imidazo[4,5-b]quinoxalinenucleus.

7. The method as described in claim 6 wherein said dye is present in aconcentration of about 10 to about 10 molar.

8. A method of producing coherent laser emission in the operation of adye laser in the wavelength range of from about 500 to about 1,000 nm.comprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom said solution containing between about 10 to about10 molar concentration of a lasing dye in a non-interfering solvent,said dye having the formula as follows:

wherein:

R represents a member selected from the group consisting of an alkylradical having one to about 10 carbon atoms, an alkenyl radical havingtwo to about 10 carbon atoms and a phenyl radical;

R represents a member selected from the group consisting of a hydrogenatom, an alkyl radical having one to about six carbon atoms and a phenylradical;

m represents an integer having a value of O, l or 2;

D and D each represent a cyano radical and when D and D are takentogether with the carbon atom to which they are attached, represent theatoms necessary to complete a 2,4,6- triketohexahydropyrimidine nucleus;and

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, athianaphtheno-7',6',4,5-thiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, a naphthoxazole nucleus, 21 selenazole nucleus, abenzoselenazole nucleus, a naphthoselenazole nucleus, a thiazolinenucleus, a 2-quinoline nucleus, a l-isoquinoline nucleus, abenzimidazole nucleus, a 3,3-dialkylindolenine nucleus, a 2-pyridinenucleus, and an imidazo[4,5-b]-quinoxaline nucleus.

9. A method of producing coherent laser emission in the operation of adye laser in the wavelength range of from about 500 to about 1,000 nm.comprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom said solution containing between about 10' to about10 molar concentration of a lasing dye in a non-interfering solvent,said dye having the formula as follows:

wherein:

R represents a member selected from the group consisting of an alkylradical having one to about 10 carbon atoms, an alkenyl radical havingtwo to about 10 carbon atoms and a phenyl radical;

R represents a member selected from the group consisting of a hydrogenatom, an alkyl radical having one to about six carbon atoms and a phenylradical;

m represents an integer having a value of O, l or 2;

l D and D each represent a cyano radical and when D and D are takentogether with the carbon atom to which they are attached, represent theatoms necessary to complete a 2,4,6- triketohexahydropyrimidine nucleus;and

Z represents the non-metallic atoms necessary to complete a heterocyclicnucleus selected from the group consisting of a thiazole nucleus, abenzothiazole nucleus, a naphthothiazole nucleus, an oxazole nucleus, abenzoxazole nucleus, a naphthoxazole nucleus and a Z-pyridine nucleus.

10. The method as described in claim 9 wherein R is an alkyl radicalhaving one or two carbon atoms.

11. A method of producing coherent laser emission in the operation ofadye laser in the wavelength range of from about 500 to about 1,000 nmcomprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom, said solution containing between about 10' to about10 molar concentration of a lasing dye in a non-interfering solvent,said dye comprising a merocyanine dye having a pyran nucleus as part ofthe intercyclic chain and said dye havingthe formula as follows:

\H RI M wherein:

and

Z represents the non-metallic atoms necessary to complete a benzoxazolenucleus.

12. The method as described in claim 11 wherein R and R each representan alkyl radical having one to about four and one to about two carbonatoms, respectively.

13. The method as described in claim 11 wherein n is O.

14. The method as described in claim 11 wherein said dye is4-dicyanomethylene-2-[ 3-ethyl-2-benzoxazolinylidene)-propenyll-o-rnethyl-4H-pyran.

methyl-4H-pyran-4-ylidene} barbituric acid; 4-dicyanomethylene-2-[(l-ethylnaphthol l,2]thiazolin- 2-ylidene)propenyll-6-methyl-4H-pyran; 4-dicyanomethylene-2-[ 3-ethyl-2-benzothiazolinylidene)propenyl]-6-methyl-4H- pyran;V4-dicyanornethylene-2-[(3-ethyl-2-benzothiazolinylidene)methyl]-6-phenyl-4H-pyran; and 1,3-diethyl-5- A W2-[ 3-ethyl-Z-benzothiaZolihylidene)prope nm-b mmethyl-4l-l-pyran-4-ylidene} barbituric acid.

2. The invention as described in claim 1 wherein said dye is present ina concentration of about 10 2 to about 10 4 molar.
 3. A dye lasercomprising means containing a laser dye solution and a pumping energysource operably coupled therewith for producing a population inversionin said solution and means optically coupled with said solution forstimulating emission therefrom during said population inversion, saiddye solution comprising a lasing concentration, in a non-interferingsolvent, of a dye having the formula as follows:
 4. A dye lasercomprising means containing a laser dye solution and a pumping energysource operably coupled therewith for producing a population inversionin said solution and means optically coupled with said solution forstimulating emission therefrom during said population inversion, saiddye solution comprising a lasing concentration, in a non-interferingsolvent, of a dye having the formula as follows:
 5. The invention asdescribed in claim 4 wherein R'' is an alkyl radical having one or twocarbon atoms.
 6. A method of producing coherent laser emission in theoperation of a dye laser in the wavelength range of from about 500 to1,000 nm comprising the step of optically pumping a dye solution toproduce a population inversion in said solution and stimulating emissionof radiation therefrom, said solution containing between about 10 2 toabout 10 4 molar concentration of a lasing dye in a non-interferingsolvent, said dye having the formula as follows:
 7. The method asdescribed in claim 6 wherein said dye is present in a concentration ofabout 10 2 to about 10 4 molar.
 8. A method of producing coherent laseremission in the operation of a dye laser in the wavelength range of fromabout 500 to about 1,000 nm. comprising the step of optically pumping adye solution to produce a population inversion in said solution andstimulating emission of radiation therefrom said solution containingbetween about 10 2 to about 10 4 molar concentration of a lasing dye ina non-interfering solvent, said dye having the formula as follows:
 9. Amethod of producing coherent laser emission in the operation of a dyelaser in the wavelength range of from about 500 to about 1,000 nm.comprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom said solution containing between about 10 2 to about10 4 molar concentratIon of a lasing dye in a non-interfering solvent,said dye having the formula as follows:
 10. The method as described inclaim 9 wherein R'' is an alkyl radical having one or two carbon atoms.11. A method of producing coherent laser emission in the operation of adye laser in the wavelength range of from about 500 to about 1,000 nmcomprising the step of optically pumping a dye solution to produce apopulation inversion in said solution and stimulating emission ofradiation therefrom, said solution containing between about 10 2 toabout 10 4 molar concentration of a lasing dye in a non-interferingsolvent, said dye comprising a merocyanine dye having a pyran nucleus aspart of the intercyclic chain and said dye having the formula asfollows:
 12. The method as described in claim 11 wherein R and R'' eachrepresent an alkyl radical having one to about four and one to about twocarbon atoms, respectively.
 13. The method as described in claim 11wherein n is
 0. 14. The method as described in claim 11 wherein said dyeis4-dicyanomethylene-2-((3-ethyl-2-benzoxazolinylidene)-propenyl)-6-methyl-4H-pyran.
 15. The method as described in claim 11 wherein said dye isselected from the group consisting of4-dicyano-methylene-2-((3-ethyl-2-benzothiazolinylidene)propenyl)-6-phenyl-4H-pyran;1,3-diethyl-5-(2-((3-ethyl-2-benzothiazolinylidene)-methyl)-6-phenyl-4H-pyran-4-ylidene) barbituric acid;4-dicyano-methylene-2-methyl-6-((1,3,3-trimethyl-2-indolinylidene)-propenyl)-4H-pyran;1,3-diethyl-5-(2-methyl-6-((1,3,3-trimethyl2-indolinylidene)propenyl)-4H-pyran-4-ylidene) barbituric acid; 1,3-diethyl-5-(2((3-ethyl-2-benzoxazolylidene)propenyl)-6methyl-4H-pyran-4-ylidene) barbituric acid;1,3-diethyl-5(2-((1-ethylnaphtho(1,2)thiazolin-2-ylidene)methyl)-6-methyl4H-pyran-4-ylidene) barbituric acid;1,3-diethyl-5-(2-((3-ethyl2-benzothiazolinylidene)methyl)-6-methyl-4H-pyran-4-ylidene)-2-thiobarbituric acid;1,3-diethyl-5-(2-((3-ethyl-2-benzothiazolinylidene)methyl)-6-methyl-4H-pyran-4-ylidene(barbituric acid; 4-dicyanomethylene-2-((1-ethylnaphtho(1,2)thiazolin-2-ylidene)propenyl)-6-methyl-4H-pyran;4-dicyanomethylene-2-((3-ethyl-2benzothiazolinylidene)propenyl)-6-methyl-4H-pyran;4-dicyanomethylene-2-((3-ethyl-2-benzothiazolinylidene)methyl)-6-phenyl4H-pyran; and1,3-diethyl-5-(2-((3-ethyl-2-benzothiazolinylidene)propenyl)-6-methyl-4H-pyran-4-ylidene) barbituric acid.